Seasoning sauces and processes for their production by fermenting protein-rich raw materials have been known in principle since antiquity.
A well known example is the seasoning sauce "garum" of the Romans, produced by fermenting fish, the flavor qualities of which are highly praised in the literature of the period, but whose recipe and production have not been passed on.
The seasoning sauces of the Chinese are older still (about 1100 B.C.); in these fish or meat was likewise first used as protein source. Soya beans or soya flour, the protein source preferred to the present day, were first mentioned in 535 B.C. The carbohydrate source needed to initiate fungal growth was a cereal product right from the beginning, usually, wheat. However, rice and barley are also mentioned in the tradition.
Other carbohydrate sources such as oats, millet, etc. are also suitable in the same way in this context, just as different protein sources can in principle be used, as the history of these seasoning sauces shows.
The combination soya/wheat is of considerable importance, these starting materials being used in different forms (whole grain, crushed, flour, roasted, etc.), depending on the soy sauce type. In general, 5 soy sauce types can be differentiated; koikuchi-, usukuchi-, tamari-, saishikomi- and shiroshoyu, which are further subdivided into three classes and differ principally in the ratio of the two base raw materials and in the production conditions.
Various flavors of seasoning sauces are achieved principally via a modification of the carbohydrate sources and of the process parameters of the production processes.
Apart from the typical aroma substances, the flavor of a soy sauce is very greatly determined by the amount of the protein and free amino acids in the solution, which are formed owing to the breakdown of protein proceeding in the fermentation to give free amino acids and peptides. A sauce having the best possible flavor should have the greatest possible amount of dissolved protein and free amino acids.
The content of dissolved protein is also termed degree of protein breakdown and is conventionally determined from the total nitrogen content (total N), taking into account the DM (dry matter) content. The content of free amino acids in a soy sauce is generally quoted as degree of hydrolysis. For premium quality soya-based sauces, a degree of protein breakdown of about 1.1-1.5% total N (at a dry matter or DM content of about 30% and a NaCl content of about 15%) and a free amino acid content (degree of hydrolysis) of greater than 50% of the protein (calculated as free amino acid/total amino acids before and after acid hydrolysis of the sauce) are customary.
The flavor of a soy sauce is also determined to a great extent by the composition of the free amino acids, some of which have sweet (serine, glycine, alanine), sulphurous (methionine) or bitter (proline, leucine, tyrosine) tastes. Phenylalanine, tryptophan and arginine have particularly intensive bitter tastes which are 5, 10 and 20 times, respectively, more bitter than leucine or proline (see H. D. Belitz et al., "Comparative Studies on the Bitter Taste of Amino Acids," Lebensmittel: Wissenschaft und Technik 5: 47-50 (1972).
In the production of an aromatic seasoning sauce having a balanced, non-bitter basic taste, these amino acids (especially arginine) should therefore be present at particularly low concentration.
There are numerous attempts to obtain special taste and aroma profiles and to increase, in particular, the content of glutamic acid.
This is achieved most simply, and, therefore, correspondingly frequently, by adding ingredients during, or (since this is still simpler) after the fermentation (e.g., by addition of sugar, spices, seasonings etc.). These sauces are also termed formulated sauces.
A higher content of glutamic acid is of interest primarily owing to the flavor enhancing properties of glutamate. In addition to the possibility of adding glutamate to the seasoning sauces, it would be more advantageous to increase the glutamic acid content by using glutamic-acid-rich raw materials or by controlling the fermentation, e.g., by using glutaminase-active starters, as described, for example, in U.S. Pat. Nos. 3,912,822 and 3,852,479.
Lupins have also already been considered as starting material for seasoning sauces in the prior art, since they have a fundamentally similar composition to soya beans and also, more precisely, with regard to their amino acid composition, as can be seen in the following Table 1.
TABLE 1 ______________________________________ Comparison between amino acid composition of soya flour (defatted) and lupin seeds %! Lupin cotyledons Soya flour* ______________________________________ Glutamic acid 21.2 19.2 Aspartic acid 10.6 11.4 Threonine 4.0 4.2 Serine 5.0 5.2 Proline 3.6 4.9 Glycine 4.2 4.4 Alanine 3.5 4.4 Valine 5.2 5.2 Methionine 0.7 1.1 Isoleucine 4.6 4.5 Leucine 8.2 8.1 Tyrosine 5.2 3.5 Phenylalanine 4.2 5.3 Lysine 5.1 6.2 Histidine 2.6 2.6 Arginine 8.6 7.3 Crude Protein content 36 44 ______________________________________ *New form
Corresponding attempts to produce a seasoning sauce based on lupin seeds were reported in 1990 at the 6th International Lupin Conference in Chile. However, the lupin seed-based products disclosed there did not have the degrees of protein breakdown usual in soy sauces, which, in addition to the type of amino acids released, are likewise important for a high taste intensity. Thus the nitrogen content as formol N was only 0.13 to 0.19% and as total N was only 0.53 to 0.66%. In contrast, a commercial soy sauce achieves degrees of protein breakdown, as formol N, of about 0.35-0.7%, and as total N, of about 1.1-1.5% (at a DM content of about 30% and a NaCl content of about 15%). This corresponds to a degree of release of amino acids of greater than 40%. More detailed analytical studies of these lupin-based seasoning sauces were not carried out. However, in a taste test, no significant difference was observed between the taste of a soy sauce and a lupin-based sauce.
Attempts to use lupin seeds instead of soya beans for the production of bean sauce and bean paste (meju) are also reported in Oh, et al., "Studies on the Fermentation of Lupin Seed (II)--Preparation of Traditional Korean Fermented Bean Sauce and Paste," Korean Journal of Applied Microbiology and Bioengineering, 11 (3): 241-248 (1983).
"Meju" is a Korean seasoning sauce which is conventionally obtained by fermenting soya beans. However, the fermentation process is fundamentally different from the production of soy sauce conventional in Japan, in particular of the koikuchi type. Although, in both cases, the fermentation process begins with a solid culture after an inoculation, preferably with Asp. oryzae, in the case of the "meju" fermentation, the solid culture is with soya beans alone, in contrast to a soya bean/carbohydrate mixture. Whereas in the case of soy sauce production, the culture is continued, after mashing, by addition of brine and inoculation with a salt-tolerant yeast, as a fermentation (in which case infection with bacteria must be largely avoided, to avoid faulty fermentation), in the "meju" case, the solid culture is continued with simultaneous drying (traditionally in the sum, otherwise, for example, for 3 days at 60.degree. C.) and a specific bacterial growth (predominantly Bacillus subtilis) is sought. There is no fermentation stage, but the "meju" is taken directly to the ripening process after mashing.
In accordance with these fermentation processes, seasoning sauces are obtained which have a very dark color, strong taste and very low pH.
Accordingly, in the Korean publication, when lupins are used in the "meju" fermentation, after ripening for two weeks, a degree of hydrolysis of 40-50% and a crude protein content (=total protein content) of 15-18% based on DM are achieved. This corresponds, at a DM content of such sauces of conventionally 20-30%, to a crude protein content of 3-5.4%, and a degree of protein breakdown of 0.48 to a maximum of 0.86%. In addition, the product made from lupins has a markedly bitter taste.
Despite the numerous products on the market of different colors, flavors, etc., there is still a requirement for novel seasoning sauces. This applies to the multiplicity of seasoning sauces known in Asia and on the market, particularly for European and American cuisine, because the products available to date still predominantly represent an Asian type of flavor (roasty, malty) and are frequently highly bitter.
An object of the present application is, therefore, to provide a seasoning sauce which can be produced on the basis of traditional fermentation technology, but which has a markedly different specific flavor profile and a higher glutamic acid content than conventional seasoning sauces based on soya beans.
A particular object of the present invention is to reduce the bitter taste of the seasoning sauce, so that it can also be used to a greater extent in European and American cuisine.
All in all, an object of the present invention is to provide a seasoning sauce as light as possible having as neutral a taste as possible.